Extremely high CPU usage that makes my system unusable?

Hey guys. I’m developing a game on Linux in UE 4.20. I’ve been developing the game on Windows for almost a year but, despite UE4 having no issues running on Windows, I switched to Linux because of accessibility needs that Windows cannot meet for me without making things more cumbersome than they have to be.

I was able to get Unreal Engine to compile under Linux perfectly fine using the Epic Wiki’s guide. My game also compiles just fine too. However, launching the editor is a different story. As soon as the editor starts to load (before the splash screen even shows up), my system immediately becomes unusable.

My window manager becomes so unresponsive I can’t even move the mouse. PulseAudio also gives up. I can see programs all over the place dimming, indicating they’ve become unresponsive. Soon enough the system is completely hosed until the editor is finished loading, to the point where I can’t even hit CTRL+ALT+F2 to get to a text-based, full-screen tty. (And if I do, I’m lucky if I can even log in and run top. You know things have hit the fan when your text-mode cursor’s blinking lags.)

I’m really not sure what’s going on here, but maybe there’s something someone else knows that I don’t.

My system:

  • CPU: AMD A10-7700K 4C+6G @ 3.4GHz
  • GPU: NVIDIA GeForce GTX 1050ti 4GB VRAM
  • RAM: 8GB DDR3
  • Storage: 240GB SSD, 1TB HDD. UE4 is on the SSD.

Linux info:

  • Kernel version: 4.18
  • Platform: amd64
  • Distro: Xubuntu 18.10
  • Desktop environment: XFCE4
  • Window manager: compiz (needed for accessibility reasons, its screen magnifier is the best of any operating system out there for multi-monitor systems.)
  • NVIDIA drivers: version 390, proprietary drivers

Development environment:

  • UE4 version: 4.20.3, compiled from source
  • IDE: Visual Studio Code
  • Debugger: lldb
  • VS Code lldb adapter: native

Below is the result of me measuring the CPU and RAM usage of the UE4Editor process from the moment I start debugging in Visual Studio Code until 4 minutes after, measured every second. I do believe at one point the engine crashed resulting in the script I was using being unable to collect all 420 samples, but, here is the output:

Left is CPU usage as a percentage. Right is RAM usage, which I SERIOUSLY hope isn’t measured in GB because if it is then, right at the end, the script said Unreal Engine was using 7.8 GB of my 8GB of RAM.

29.0  0.8
48.5  1.6
32.3  1.6
24.2  0.8
19.4  0.2
16.1  0.2
13.8  0.2
12.1  0.2
10.7  0.2
 9.7  0.1
 8.8  0.1
 8.0  0.1
 7.4  0.1
 5.1  0.1
 4.8  0.1
 4.4  0.1
 3.8  0.1
 3.7  0.1
 3.5  0.1
 3.3  0.1
 3.2  0.1
 3.1  0.1
 3.0  0.1
 2.9  0.1
 2.8  0.1
 2.6  0.1
 2.6  0.1
 2.5  0.1
 2.4  0.1
 2.4  0.1
 2.3  0.1
 2.2  0.1
 2.0  0.1
 1.9  0.1
 1.7  0.1
 1.7  0.1
 1.6  0.1
 1.6  0.1
 1.6  0.1
 1.5  0.1
 1.5  0.1
 1.5  0.1
 1.4  0.1
 1.4  0.1
 1.4  0.1
 1.4  0.1
 1.3  0.1
 1.3  0.1
 1.3  0.1
 1.2  0.1
 1.2  0.1
 1.2  0.1
 1.1  0.1
 1.1  0.1
 1.0  0.1
 1.0  0.1
 1.0  0.1
 1.0  0.1
 1.0  0.1
 1.0  0.1
 1.0  0.1
 0.9  0.1
 0.9  0.1
 0.9  0.1
 0.9  0.1
 0.9  0.1
 0.9  0.1
 0.9  0.1
 0.9  0.1
 0.8  0.1
 0.8  0.1
 0.8  0.1
 0.8  0.1
 0.8  0.1
 0.8  0.1
 0.8  0.1
 0.8  0.1
 0.8  0.1
 0.8  0.1
 0.8  0.1
 0.7  0.1
 0.7  0.1
 0.7  0.1
 0.7  0.1
 0.7  0.1
 0.7  0.1
 0.7  0.1
 0.7  0.1
 0.7  0.1
 0.7  0.1
 0.7  0.1
 0.7  0.1
 0.7  0.1
 0.6  0.1
 0.6  0.1
 0.6  0.1
 0.6  0.1
 0.6  0.1
 0.6  0.1
 0.6  0.1
 0.6  0.1
 0.6  0.1
 0.6  0.1
 0.5  0.1
 0.5  0.1
 0.5  0.1
 0.5  0.1
 0.5  0.1
 0.6  0.4
 0.8  0.8
 0.9  0.6
 0.9  0.6
 1.0  0.9
 1.1  0.5
 1.1  0.4
 1.1  0.5
 1.5  0.7
 1.8  0.6
 2.1  0.7
 2.3  0.5
 2.4  0.5
 2.6  0.6
 2.6  0.6
 2.7  0.6
 2.8  0.6
 3.1  0.8
 3.3  0.8
 3.3  1.1
 3.3  1.0
 3.3  0.8
 3.3  0.9
 3.4  1.1
 3.6  1.3
 3.6  1.4
 3.7  1.9
 3.9  2.8
 3.9  2.8
 4.1  2.7
 4.5  2.6
 4.7  3.0
 4.8  3.0
 5.1  3.2
 5.4  3.2
 5.8  3.2
 5.9  3.2
 6.1  3.1
 6.5  3.0
 6.7  3.3
 7.0  3.3
 7.2  3.1
 7.5  3.1
 7.7  3.2
 8.0  3.0
 8.1  3.3
 8.1  3.3
 8.1  3.0
 8.1  3.0
 8.1  3.2
 8.0  3.6
 8.1  4.6
 8.1  4.7
 8.1  5.2
 8.1  5.3
 8.1  5.3
 8.1  5.5
 8.5  5.8
 8.9  6.6
 9.4  6.9
 9.9  6.8
10.2  6.6
10.6  6.4
10.7  6.4
10.8  6.2
11.2  6.5
11.6  6.6
12.0  6.5
12.4  6.8
12.7  6.9
13.1  7.2
13.5  7.2
14.0  7.2
14.4  7.3
15.3  8.3
15.6  8.2
16.0  8.0
16.3  7.8
16.7  8.0
17.1  7.9
17.5  7.7
17.9  8.1
18.0  8.1
18.4  8.4
18.7  8.1
18.9  8.3
19.2  8.1
19.5  8.1
19.7  8.2
20.0  7.8
20.3  7.8
20.7  7.8
21.4  7.8

I have also noticed that, while the editor starts, if I go into my tty, I sometimes get kernel messages saying audit: backlog limit reached. Not sure what that means.

Whatever’s going on, I hope there’s something I can do to fix it. I can’t give up Linux OR Unreal Engine 4.